$A$ certain sum of money amounts to ₹ $918$ in $2$ $years$ and ₹ $969$ in $3.5$ $years$ at simple interest. What is the rate of interest (in $\%$ $p.a.$)?

When the rate of interest in a bank is reduced from $5 \%$ p.a. to $4.5 \%$ p.a.,Bani deposited $Rs. 4000$ in her savings account. She found that the new interest income remained the same as before. Find her original deposit (in $Rs.$)?

Anil invested an amount for $3$ $years$ at a simple interest rate of $9$ $p.c.p.a.$ He got an amount of $Rs. 19050$ at the end of $3$ $years.$ What principal amount (in $Rs.$) did he invest?

Suhit borrowed a sum of $Rs. 6300$ from Vikas at the rate of $14 \%$ per annum for $3$ years. He then added some more money to the borrowed sum and lent it to Mohit at the rate of $16 \%$ simple interest for the same time. If Suhit gained $Rs. 618$ in the whole transaction,what sum did he lend (in $Rs.$) to Mohit?

Reena took a loan of ₹ $1,200$ with simple interest for as many years as the rate of interest. If she paid ₹ $432$ as interest at the end of the loan period,what was the rate of interest?

Heena invests an amount of $10250$ at $4$ $p.c.p.a.$ to obtain a total amount of $Rs. 12710$ on simple interest after a certain period. For how many years did she invest the amount to obtain the total sum?